JPH06123314A - Oil-impregnated sintered bearing - Google Patents

Abstract

PURPOSE:To restrict the reduction of the oil film of sliding surfaces of an oil-impregnated sintered bearing, and facilitate the circumferential positioning of the sliding surfaces and a rotary shaft to be inserted to the bearing. CONSTITUTION:In oil-impregnated sintered bearing 10, a bearing main body 11 made of porous sintered alloy is formed with a bearing hole, in which a rotary shaft 2 is to be inserted. In this oil-impregnated sintered bearing 10, a side of the inner peripheral surface of the hole, where the rotary shaft 12 slides for movement, among the inner peripheral surface of the bearing hole is crushed in the axial direction of the bearing main body 11 at the time of green formation of the bearing main body 11 to form sliding surface S1, S2, and a notch part or a projection part is formed at a position having a predetermined relation with the sliding surfaces S1, S2 of the outer peripheral surface of the bearing main body 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered oil-impregnated bearing, and more particularly to a sintered oil-impregnated bearing having excellent friction characteristics.

[0002]

2. Description of the Related Art Sintered oil-impregnated bearings, which are made of a porous sintered alloy and impregnated with lubricating oil, can be used for a long time without lubrication and are therefore widely used as bearings for rotary shafts of various equipment. Has been.

As shown in FIG. 3, a sintered oil-impregnated bearing 1 of this type has a bearing body 2 made of a porous sintered alloy.
The rotary shaft 4 having a smaller diameter than that of the bearing hole 3 is inserted into the bearing hole 3 formed in the bearing hole 3 and is sucked out from a large number of fine oil-impregnated holes (holes) of the bearing body 2 by the pumping action accompanying the rotation of the rotary shaft 4. The lubricating oil and the lubricating oil that oozes out due to expansion due to frictional heat form an oil film on the sliding surface 5 of the bearing hole 3, and the oil film rotatably supports the rotating shaft 4. .

[0004]

By the way, in the above sintered oil-impregnated bearing, a large number of holes for impregnating lubricating oil are formed on the sliding surface 5 of the bearing hole 3 on which the rotary shaft 4 slides. Even if an oil film is formed, a part of the lubricating oil leaks from the holes to reduce the hydraulic pressure, and as a result, the rotating shaft 4 and the sliding surface 5 are locally brought into contact with each other. Thus, there is a drawback that the friction coefficient of the oil-impregnated bearing increases when the local contact is performed.

On the other hand, in order to solve such a problem, for example, a technique disclosed in Japanese Utility Model Laid-Open No. 50-101735 has been proposed.

According to this technique, of the inner peripheral surface of the bearing main body, a substantially half-circumferential portion to which a load is applied is crushed to suppress the leakage of lubricating oil from the sliding surface with the rotating shaft to reduce the oil film. This is to prevent it.

However, even in such a technique, the following problems still remain.

That is, in the above-mentioned prior art, since the bearing is crushed over approximately half the circumference of the bearing body, when the sintered oil-impregnated bearing is mounted on equipment, the load direction of the rotary shaft is aligned with the crushed portion. This is a problem that the work must be done (the blind portion must be located in front of the load direction), and the work is complicated.

In addition, when the above-mentioned crushing is performed, the curvature of the part of the bearing hole to be crushed is made small and the crushing is performed by cutting so that the curvature of this part matches the curvature of the other part. As a result, the number of production processes is increased, and work is complicated in terms of production.

[0010]

SUMMARY OF THE INVENTION The present invention provides a sintered oil-impregnated bearing capable of effectively solving the problems remaining in the above-mentioned conventional techniques. In a sintered oil-impregnated bearing in which a bearing hole for inserting a rotary shaft is formed in a bearing body formed of a coupling metal, an inner peripheral surface of the inner peripheral surface of the bearing hole on the side on which the rotary shaft slides The hole of the bearing body is crushed in the axial direction of the bearing body during powder molding to form a sliding surface, and at a position having a predetermined positional relationship with the sliding surface of the outer peripheral surface of the bearing body, It is characterized in that a notch portion or a convex portion is formed.

[0011]

The sintered oil-impregnated bearing of the present invention can be assembled while checking the position of the sliding surface by assembling with reference to the notches and protrusions formed on the outer peripheral surface. Further, since the holes of the sliding surface are crushed during the powder compacting of the bearing body, the plastic deformation of the sliding surface is smoothly performed, and the holes are reliably crushed.

[0012]

EXAMPLE An example of a sintered oil-impregnated bearing according to the present invention will be described below. The sintered oil-impregnated bearing 10 shown in FIG. 1 has a bearing body 11 made of a porous sintered alloy, a rotary shaft 12
The bearing shaft 13 is formed so that the rotating shaft 12 is stopped within a range of a half circumference of the inner peripheral surface of the bearing hole 13 on which the rotating shaft 12 slides. At a plurality of circumferentially symmetrical points (sliding surfaces indicated by S1 and S2 in FIG. 1) in the circumferential direction around the contact point Z at the time By crushing, the lubricating oil is prevented from leaking from the sliding surfaces S1 and S2, and the inner surface between these sliding surfaces S1 and S2 is an oil supply portion P in which holes are left. .

On the outer peripheral surface of the bearing body 11, at a midpoint between the sliding surfaces S1 and S2, that is, on the opposite side of the contact point Z (that is, at a position of 180 ° in the circumferential direction),
A concave groove 14 is formed along the length direction of the bearing body 11.

Next, a method for manufacturing the sintered oil-impregnated bearing will be described. First, as shown in FIG. 5, the cylindrical lower punch 16 is positioned at a predetermined position in the die 15 of the die set used for normal powder molding, and the cylindrical core rod 17 is attached to the upper surface of the die 15. And make it flush. At this time, the upper punch 18 is made to stand by above the die 15.

Here, in the outer peripheral surface of the core rod 17,
Twisted portions 19 having a surface roughness higher than those of other portions are formed at two locations spaced apart in the circumferential direction (only one location is shown in the drawing). These rough parts 1
9 is formed to extend in a belt shape in the axial direction of the core rod 17, and is formed to be slightly recessed from the outer peripheral surface of the core rod 17.

The circumferential width of each of the roughened portions 19 is determined by sliding along the axial direction in which the rotary shaft 12 slides on the inner peripheral surface of the bearing hole 13 of the sintered oil-impregnated bearing to be manufactured. Surface S
It is set to a size corresponding to the width of 1 · S2, specifically, a width that allows for shrinkage due to sintering of the green compact to be molded, and the sliding surface S1 · S2 It is formed with an interval that allows for the above-mentioned contraction in accordance with the interval.

The roughened portion 19 is formed by electric discharge machining, and a large number of fine convex portions are formed on the surface thereof. The surface roughness of the roughened portion 19 is appropriately selected according to the particle diameter of the powder to be molded, but in this embodiment, it is 5 to 5.
It is set to 10S.

Further, the upper punch 18 and the lower punch 16
On the outer surface of the bearing main body 11, concave grooves 18a and 16a having substantially the same shape as the concave groove 14 of the bearing main body 11 are formed along the length direction thereof. The ridges 20 having substantially the same cross-sectional shape are formed along the longitudinal direction, and the ridges 20 and the grooves 18a and 16a are adapted to be fitted to each other at the time of powder compacting,
On the other hand, the core rod 17 is 180 ° in the circumferential direction.
It is designed to be aligned with the position.

Thus, after the powder is filled in the die 15, the upper punch 18 is lowered into the die 15 to compress the powder into a cylindrical shape. At this time, since the roughened portions 19 are formed at two positions of the core rod 17, the holes on the surface of the green compact which are in contact with these roughened portions 19 are
The peripheral portions of the holes are pressed by the large number of convex portions of each roughened portion 19 and plastically flow into the holes to be crushed. Also, the roughened part 1
Since 9 is slightly recessed as described above, the portion in contact with the roughened portion 19 of the molded green compact, that is, the sliding surface 13
The part that becomes is slightly protruding.

Then, the green compact thus formed is taken out from the die 15 and sintered at a predetermined temperature to obtain a sintered body. This sintered body has sliding surfaces S1 and S2 when pressed.
Since the holes on the surface corresponding to are crushed, the holes 13 on each of the sliding surfaces S1 and S2 of the sintered body are crushed, and both sliding surfaces S1
The holes of the bearing hole 13 between and on both sides of S2 are left, and further, on the outer peripheral surface at a position 180 ° apart from the sliding surfaces S1 and S2, a concave groove along the length direction of the bearing hole 13 is formed. 14 is formed.

Then, this sintered body is incorporated into a die set (not shown) similar to the above, and compressed and subjected to a sizing process to correct each part of the sintered body to manufacture a sintered oil-impregnated bearing. . During the sizing process, the slightly protruding sliding surfaces S1 and S2 are pressed by the core rod of the die set to be flush with the inner peripheral surface of the bearing hole 13, and the sliding surfaces S1 and S2 are also formed. Is smoothed, and the groove 14 is further smoothed by the die set.

According to the sintered oil-impregnated bearing 10, however, the positions of the sliding surfaces S1 and S2 are confirmed by the concave groove 14 formed on the outer peripheral surface. By assembling to the equipment, the sliding surfaces S1 and S2 can be easily positioned with respect to the load direction of the rotary shaft 12. This ensures that the rotary shaft 12 can slide the sliding surface S
Since it is opposed to 1 and S2, a reliable lubricating action can be obtained.

Further, of the inner peripheral surface of the bearing hole 13, the rotary shaft 1
The holes on the sliding surfaces S1 and S2 along the axial direction in which 2 slides are crushed, and this crushing is performed during the powder compaction of the bearing body 11, so that the holes can be reliably crushed. As a result, the lubricating oil on the sliding surfaces S1 and S2 does not leak. Therefore, a strong oil film is formed on the sliding surfaces S1 and S2 so that the hydraulic pressure does not decrease.
The lubricating oil is sufficiently supplied to the rotary shaft 12 from the holes on the inner peripheral surface of the bearing hole 13 located between the sliding surfaces S1 and S2 and on both sides of the sliding surfaces S1 and S2. Therefore, since the rotating shaft 12 and the sliding surface 13 are not locally contacted with each other, it is possible to reduce the friction coefficient of the oil-impregnated bearing and obtain bearing characteristics with a high use limit.

Further, in this embodiment, since the sliding surfaces S1 and S2 are formed at two symmetrical positions in the circumferential direction around the contact point Z when the rotary shaft 12 is stopped, the rotary shaft 12 is formed. When the rotary shaft 12 rotates in one direction and becomes a steady state, the rotary shaft 12 faces one sliding surface S1, and when it rotates in the opposite direction, the rotary shaft 12 faces the other sliding surface S2. To be

As a result, when the rotary shaft 12 rotates in both the forward and reverse directions, even if the center axis of the rotary shaft 12 is displaced, the rotary shaft 12 can be reliably moved by the sliding surface S1 of the bearing body 11.
・ It will be opposed to S2. Therefore, in combination with the smooth supply of the lubricating oil described above, an oil-impregnated bearing having a small friction coefficient can be obtained.

Furthermore, when molding the green compact, the sliding surface S1
Since the hole in the portion to be S2 is crushed, the plastic deformation of the sliding surface S1, S2 is smoothly performed, and the hole is reliably crushed, and the sliding surface S1, S2 is There is an advantage that a sintered oil-impregnated bearing can be manufactured by a process exactly the same as the conventional process, without newly providing a process of crushing the holes.

In the above embodiment, the roughened portion 19 is formed on the core rod 17 by using electric discharge machining. However, the invention is not limited to this, and the roughened portion 19 may be formed by machining with a knurl or the like. .

Further, in the above-mentioned embodiment, the example in which the concave groove 14 is formed on the outer peripheral surface has been described, but as shown in FIG. 2, the outer peripheral surface is formed with the notch 21 in parallel with the axial direction of the bearing body 11. The same effect can be obtained by forming a flat portion, and a convex strip can be used instead of the concave groove 14 and the notch 21.

[0029]

As described above, according to the sintered oil-impregnated bearing of the present invention, a bearing main body made of a porous sintered alloy is provided with a bearing hole through which a rotary shaft is inserted. In the oil-impregnated bearing, of the inner peripheral surface of the bearing hole, the hole on the inner peripheral surface on the side where the rotary shaft slides is crushed in the axial direction of the bearing main body during powder compaction of the bearing main body and slides. In addition to forming a surface, a notch portion or a convex portion is formed at a position having a predetermined positional relationship with the sliding surface of the outer peripheral surface of the bearing main body. It has an excellent effect.

The position of the sliding surface can be confirmed by the cutouts or projections formed on the outer peripheral surface, and the rotary shaft is assembled by assembling to the equipment with reference to these cutouts or projections. The sliding surface can be easily positioned in the direction of the load. As a result, the rotary shaft can be reliably opposed to the sliding surface, and a reliable lubricating action can be obtained.

Further, when the green compact is molded, the pores of the sliding surface are crushed, so that the plastic deformation of the sliding surface is smoothed and the crushing of the pores is ensured. In addition, it is not necessary to newly provide the step of crushing the holes on the sliding surface after sintering, and the sintered oil-impregnated bearing can be manufactured by the same step as the conventional one, and the step is simplified. .

[Brief description of drawings]

FIG. 1 is a front view of a sintered oil-impregnated bearing according to an embodiment of the present invention.

FIG. 2 is a front view of a sintered oil-impregnated bearing according to another embodiment of the present invention.

FIG. 3 is a vertical sectional view of a conventional oil-impregnated sintered bearing.

FIG. 4 is a sectional view taken along the line AA in FIG.

FIG. 5 is a cross-sectional view of a main part of a die set for explaining a method for manufacturing a sintered oil-impregnated bearing according to the present invention.

[Explanation of symbols]

 10 Sintered oil-impregnated bearing 11 Bearing body 12 Rotating shaft 14 Recessed groove 21 Notch S1 ・ S2 Sliding surface P Oil supply part Z Contact point when the rotating shaft is stopped

Front Page Continuation (72) Inventor Satoshi Murayama 1 3-3, Kogane-cho, Niigata City, Niigata Prefecture Mitsubishi Material Co., Ltd. Niigata Plant (72) Inventor Takeshi Tanaka 390 Umeda, Kosai City, Shizuoka Asmo Stock Company In-house (72) Invention Person Daisuke Oba 390 Umeda, Kosai City, Shizuoka Asmo Stock Association In-house

Claims (1)

[Claims] 1. A sintered oil-impregnated bearing in which a bearing main body made of a porous sintered alloy is formed with a bearing hole through which a rotary shaft is inserted. The hole on the inner peripheral surface on the side where the shaft slides is crushed in the axial direction of the bearing body during powder compaction of the bearing body to form a sliding surface, and the sliding surface on the outer peripheral surface of the bearing body. A sintered oil-impregnated bearing characterized in that a notch or a protrusion is formed at a position having a predetermined positional relationship with.